The general construction of biomedical electrodes of this general type is described in U.S. Pat. No. 3,973,557, issued Aug. 10, 1976, to Kenneth C. Allison.
Biomedical electrodes are used in direct contact with skin surfaces of subjects. When a biomedical electrode is applied to the skin of a subject, the subject may perspire under the electrode. Perspiration formed under the diaphragm of a biomedical electrode employing a liquid electrolyte simply mixes with electrolyte, which permeates the diaphragm. Perspiration is also released under the electrode mount as well. In order to maintain the comfort of the subject, as well as adhesive connection of the mount with the skin, it is desirable that the moisture from the perspiration is released from the electrode mount. One method of releasing the moisture is disclosed in U.S. Pat. No. 3,973,557 to Allison. An open-cell foam, having a network adhesive, is employed for the electrode mount. The moisture migrates past the network adhesive, through the pores of the open-cell foam, and evaporates from the top of the mount. Open-cell foams are, however, somewhat more expensive than closed-cell foams. Likewise, network adhesive is somewhat more expensive to purchase and to apply than a uniform adhesive.
It is also apparent that the electrode mount must be secured to the container. One method of securing the electrode mount to the container is by heat sealing. Both the electrode mount and the container are composed of plastic, which can be fused together by heat sealing. Heat sealing of the foam mounting pad to the container can be a delicate operation. The sealing temperature must be carefully controlled. If the temperature is too high, the mounting pad will melt and tear. If the temperature is too low, the heat sealing will not be complete.
What is needed, then, is an electrode which uses relatively inexpensive closed-cell foam mounting pads and uniform adhesive while allowing perspiration to evaporate from a subject. In addition, the electrode mount should be secured to the container by a mechanical lock.